1. Field of the Invention
The present invention relates to a touch display device having an optical touch panel and a touch input method thereof, and more particularly, to an optical touch panel which comprises only a single planar light generator and a single photo sensor array, and to the touch display device which includes the optical touch panel mentioned above and a touch input method thereof.
2. Description of the Prior Art
In all kinds of consumer electronic products of nowadays, the mobile electronic products, such as tablet computer, personal digital assistance (PDA), mobile phone and global position system (GPS), have widely adopted touch panel as human machine interface to reduce the volume of the electronic products.
Generally, according to the difference of the touch input mechanisms, touch panels can be classified into resistive touch panel, capacitive touch panel, and optical touch panel. Among all these types of touch panels, because of the advantages of long lifetime, high light transmittance, and so on, the optical touch panels have been widely applied to various kinds of electronic products.
FIG. 1 illustrates a schematic diagram of a conventional optical touch panel. As shown in FIG. 1, the conventional optical touch panel 10 includes a substrate 12, a first light generator 141 disposed in a first corner 181 of the substrate 12, a second light generator 142 disposed in a second corner 182 of the substrate 12, a first light receiver 161 disposed in the first corner 181 of the substrate 12, and a second light receiver 162 disposed in a second corner 182. When inputting at an input point A by a touch input device, such as a touch pen (which is not shown in FIG. 1), a light emitted by the first light generator 141 is reflected by the touch input device and received by the first light receiver 161 so that a first included angle γ1 between a connected line of the first corner 181 and the input point A and a side L of the substrate 12 is obtained. Also, a light emitted by the second light generator 142 is reflected by the touch input device and received by the second light receiver 162 so that a second included angle γ2 between a connected line of the second corner 182 and the touch input point A and the side L of the substrate 12 is obtained. Therefore, as a length W of the side L of the substrate 12 is known, a horizontal coordinate x and a vertical coordinate y of the input point A can be calculated by the following equations (A) and (B).
                    x        =                              W            ⁢                                                  ⁢            tan            ⁢                                                  ⁢            γ            ⁢                                                  ⁢            2                                              tan              ⁢                                                          ⁢              γ              ⁢                                                          ⁢              1                        +                          tan              ⁢                                                          ⁢              γ              ⁢                                                          ⁢              2                                                          equation        ⁢                                  ⁢                  (          A          )                                        y        =                  x          ⁢                                          ⁢          tan          ⁢                                          ⁢          γ          ⁢                                          ⁢          1                                    equation        ⁢                                  ⁢                  (          B          )                    
Accordingly, the conventional optical touch panel must have at least two light generators and at least two light receivers to calculate the correct input position. However, the increase in light generators and light receivers represents the increase in the cost of the product and the complication of the process.